GETTYSBURG, Pa. (AP) - As Illinois Republicans vote in the state's presidential primary, GOP hopeful Rick Santorum is reconnecting with a son of Illinois remembered for one afternoon he spent in Pennsylvania.

Santorum plans to watch Tuesday's results from Illinois at a campaign party in Gettysburg, Pa., the venue for President Abraham Lincoln's famous Civil War address.

Santorum had campaigned in Illinois and looks to continue his trend of doing well in rural, conservative areas while largely ceding urban areas to Republican front-runner Mitt Romney.

Santorum aides cast his decision to return to Pennsylvania as a nod to Illinois' famous son. It's also a political move. Santorum represented Pennsylvania in the House and the Senate, and his aides have said he must do well there to continue a campaign that lags behind Romney in terms of money, organization and delegates.

Heading into Tuesday, The Associated Press delegate count showed Romney had amassed 521 delegates. Santorum had 253, former House Speaker Newt Gingrich had 136 and Rep. Ron Paul of Texas had 50.

Romney is on pace to collect the 1,144 delegates needed to win the nomination in June unless Santorum or Gingrich is able to start posting decisive wins. Neither Santorum nor Gingrich has signaled he will exit the race. That could mean they will continue to split the vote of conservatives voters who have never warmed to Romney.